ScanLeft

Alias for concat.

Type parameters

B: the element type of the returned collection

Value parameters

suffix: the iterable to append to this view

Attributes

Inherited from:: IterableOps
Source: Iterable.scala

Appends all elements of this view to a string builder. The written text consists of the string representations (w.r.t. the method toString) of all elements of this view without any separator string.

Example:

    val a = List(1,2,3,4) // List(1, 2, 3, 4)
    val b = new StringBuilder()
    val h = a.addString(b) // 1234

Value parameters

b: the string builder to which elements are appended.

Attributes

Returns: the string builder b to which elements were appended.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Appends all elements of this view to a string builder using a separator string. The written text consists of the string representations (w.r.t. the method toString) of all elements of this view, separated by the string sep.

Example:

    val a = List(1,2,3,4) // List(1, 2, 3, 4)
    val b = new StringBuilder()
    a.addString(b, ", ") // 1, 2, 3, 4

Value parameters

b: the string builder to which elements are appended.
sep: the separator string.

Attributes

Returns: the string builder b to which elements were appended.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Appends all elements of this view to a string builder using start, end, and separator strings. The written text begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this view are separated by the string sep.

Example:

    val a = List(1,2,3,4) // List(1, 2, 3, 4)
    val b = new StringBuilder()
    a.addString(b , "List(" , ", " , ")") // List(1, 2, 3, 4)

Value parameters

b: the string builder to which elements are appended.
end: the ending string.
sep: the separator string.
start: the starting string.

Attributes

Returns: the string builder b to which elements were appended.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Builds a new view by applying a partial function to all elements of this view on which the function is defined.

Type parameters

B: the element type of the returned view.

Value parameters

pf: the partial function which filters and maps the view.

Attributes

Returns: a new view resulting from applying the given partial function pf to each element on which it is defined and collecting the results. The order of the elements is preserved.
Inherited from:: IterableOps
Source: Iterable.scala

Finds the first element of the view for which the given partial function is defined, and applies the partial function to it.

Note: may not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Type parameters

B: the result type of the partial function

Value parameters

pf: the partial function

Attributes

Returns: an option value containing pf applied to the first value for which it is defined, or None if none exists.
Example: Seq("a", 1, 5L).collectFirst { case x: Int => x*10 } = Some(10)
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Returns a new view containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the view is the most specific superclass encompassing the element types of the two operands.

Type parameters

B: the element type of the returned collection.

Value parameters

suffix: the iterable to append.

Attributes

Returns: a new view which contains all elements of this view followed by all elements of suffix.
Inherited from:: IterableOps
Source: Iterable.scala

Copies elements to an array and returns the number of elements written.

Fills the given array dest starting at index start with at most n elements of this view.

Copying will stop once either all the elements of this view have been copied, or the end of the array is reached, or n elements have been copied.

If start is less than zero, it is taken as zero.

Type parameters

B: the type of the elements of the array.

Value parameters

dest: the array to fill.
n: the maximal number of elements to copy.
start: the starting index of xs.

Attributes

Returns: the number of elements written to the array
Note: Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Copies elements to an array, returning the number of elements written.

Fills the given array dest starting at index start with values of this view.

Copying will stop once either all the elements of this view have been copied, or the end of the array is reached.

Type parameters

B: the type of the elements of the array.

Value parameters

dest: the array to fill.
start: the starting index of xs.

Attributes

Returns: the number of elements written to the array
Note: Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Copies elements to an array, returning the number of elements written.

Fills the given array dest starting at index start with values of this view.

Copying will stop once either all the elements of this view have been copied, or the end of the array is reached.

Type parameters

B: the type of the elements of the array.

Value parameters

dest: the array to fill.

Attributes

Returns: the number of elements written to the array
Note: Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.

Note: will not terminate for infinite-sized collections.

Type parameters

B: the type of the elements of that

Value parameters

p: the test predicate, which relates elements from both collections
that: the other collection

Attributes

Returns: true if both collections have the same length and p(x, y) is true for all corresponding elements x of this iterator and y of that, otherwise false
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Counts the number of elements in the view which satisfy a predicate.

Note: will not terminate for infinite-sized collections.

Value parameters

p: the predicate used to test elements.

Attributes

Returns: the number of elements satisfying the predicate p.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Selects all elements except the first n ones.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters

n: the number of elements to drop from this view.

Attributes

Returns: a view consisting of all elements of this view except the first n ones, or else the empty view, if this view has less than n elements. If n is negative, don't drop any elements.
Inherited from:: IterableOps
Source: Iterable.scala

Selects all elements except last n ones.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters

n: the number of elements to drop from this view.

Attributes

Returns: a view consisting of all elements of this view except the last n ones, or else the empty view, if this view has less than n elements. If n is negative, don't drop any elements.
Inherited from:: IterableOps
Source: Iterable.scala

Selects all elements except the longest prefix that satisfies a predicate.

The matching prefix starts with the first element of this view, and the element following the prefix is the first element that does not satisfy the predicate. The matching prefix may be empty, so that this method returns the entire view.

Example:

    List(1, 2, 3, 100, 4).dropWhile(n => n < 10) // List(100, 4)
    List(1, 2, 3, 100, 4).dropWhile(n => n == 0) // List(1, 2, 3, 100, 4)

Use span to obtain both the prefix and suffix. Use filterNot to drop all elements that satisfy the predicate.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters

p: The predicate used to test elements.

Attributes

Returns: the longest suffix of this view whose first element does not satisfy the predicate p.
Inherited from:: IterableOps
Source: Iterable.scala

The empty view.

Attributes

Returns: an empty iterable of type View .
Definition Classes: View -> IterableFactoryDefaults -> IterableOps
Inherited from:: View
Source: View.scala

Tests whether a predicate holds for at least one element of this view.

Note: may not terminate for infinite-sized collections.

Value parameters

p: the predicate used to test elements.

Attributes

Returns: true if the given predicate p is satisfied by at least one element of this view, otherwise false
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Selects all elements of this view which satisfy a predicate.

Value parameters

p: the predicate used to test elements.

Attributes

Returns: a new view consisting of all elements of this view that satisfy the given predicate p. The order of the elements is preserved.
Inherited from:: IterableOps
Source: Iterable.scala

Selects all elements of this view which do not satisfy a predicate.

Value parameters

pred: the predicate used to test elements.

Attributes

Returns: a new view consisting of all elements of this view that do not satisfy the given predicate pred. Their order may not be preserved.
Inherited from:: IterableOps
Source: Iterable.scala

Finds the first element of the view satisfying a predicate, if any.

Note: may not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters

p: the predicate used to test elements.

Attributes

Returns: an option value containing the first element in the view that satisfies p, or None if none exists.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Builds a new view by applying a function to all elements of this view and using the elements of the resulting collections.

For example:

    def getWords(lines: Seq[String]): Seq[String] = lines.flatMap(line => line.split("\\W+"))

The type of the resulting collection is guided by the static type of this view. This might cause unexpected results sometimes. For example:

    // lettersOf will return a Seq[Char] of likely repeated letters, instead of a Set
    def lettersOf(words: Seq[String]) = words.flatMap(word => word.toSet)

    // lettersOf2 will return a Set[Char], not a Seq
    def lettersOf2(words: Seq[String]) = words.toSet.flatMap(word => word.toSeq)

    // xs will be an Iterable[Int]
    val xs = Map("a" -> List(11, 111), "b" -> List(22, 222)).flatMap(_._2)

    // ys will be a Map[Int, Int]
    val ys = Map("a" -> List(1 -> 11, 1 -> 111), "b" -> List(2 -> 22, 2 -> 222)).flatMap(_._2)

Type parameters

B: the element type of the returned collection.

Value parameters

f: the function to apply to each element.

Attributes

Returns: a new view resulting from applying the given collection-valued function f to each element of this view and concatenating the results.
Inherited from:: IterableOps
Source: Iterable.scala

Given that the elements of this collection are themselves iterable collections, converts this view into a view comprising the elements of these iterable collections.

The resulting collection's type will be guided by the type of view. For example:

  val xs = List(
             Set(1, 2, 3),
             Set(1, 2, 3)
           ).flatten
  // xs == List(1, 2, 3, 1, 2, 3)

  val ys = Set(
             List(1, 2, 3),
             List(3, 2, 1)
           ).flatten
  // ys == Set(1, 2, 3)

Type parameters

B: the type of the elements of each iterable collection.

Value parameters

asIterable: an implicit conversion which asserts that the element type of this view is an Iterable.

Attributes

Returns: a new view resulting from concatenating all element collections.
Inherited from:: IterableOps
Source: Iterable.scala

Applies the given binary operator op to the given initial value z and all elements of this view.

For each application of the operator, each operand is either an element of this view, the initial value, or another such application of the operator.

        The order of applications of the operator is unspecified and may be nondeterministic.
        Each element appears exactly once in the computation.

The initial value may be used an arbitrary number of times, but at least once.

If this collection is ordered, then for any application of the operator, the element(s) appearing in the left operand will precede those in the right.

        Note: might return different results for different runs, unless either
        of the following conditions is met: (1) the operator is associative,
        and the underlying collection type is ordered; or (2) the operator is
        associative and commutative. In either case, it is also necessary that the initial value

be a neutral value for the operator, e.g. Nil for List concatenation or 1 for multiplication.

The default implementation in IterableOnce is equivalent to foldLeft but may be overridden for more efficient traversal orders.

Note: will not terminate for infinite-sized collections.

Type parameters

A1: The type parameter for the binary operator, a supertype of A.

Value parameters

op: A binary operator; must be associative for the result to always be the same across runs.
z: An initial value; may be used an arbitrary number of times in the computation of the result; must be a neutral value for op for the result to always be the same across runs.

Attributes

Returns: The result of applying op between all the elements and z, or z if this view is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Applies the given binary operator op to the given initial value z and all elements of this view, going left to right. Returns the initial value if this view is empty.

"Going left to right" only makes sense if this collection is ordered: then if x,,1,,, x,,2,,, ..., x,,n,, are the elements of this view, the result is op( op( ... op( op(z, x,,1,,), x,,2,,) ... ), x,,n,,).

If this collection is not ordered, then for each application of the operator, each right operand is an element. In addition, the leftmost operand is the initial value, and each other left operand is itself an application of the operator. The elements of this view and the initial value all appear exactly once in the computation.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The result type of the binary operator.

Value parameters

op: A binary operator.
z: An initial value.

Attributes

Returns: The result of applying op to z and all elements of this view, going left to right. Returns z if this view is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Applies the given binary operator op to all elements of this view and the given initial value z, going right to left. Returns the initial value if this view is empty.

"Going right to left" only makes sense if this collection is ordered: then if x,,1,,, x,,2,,, ..., x,,n,, are the elements of this view, the result is op(x,,1,,, op(x,,2,,, op( ... op(x,,n,,, z) ... ))).

If this collection is not ordered, then for each application of the operator, each left operand is an element. In addition, the rightmost operand is the initial value, and each other right operand is itself an application of the operator. The elements of this view and the initial value all appear exactly once in the computation.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The result type of the binary operator.

Value parameters

op: A binary operator.
z: An initial value.

Attributes

Returns: The result of applying op to all elements of this view and z, going right to left. Returns z if this view is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Tests whether a predicate holds for all elements of this view.

Note: may not terminate for infinite-sized collections.

Value parameters

p: the predicate used to test elements.

Attributes

Returns: true if this view is empty or the given predicate p holds for all elements of this view, otherwise false.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Applies f to each element for its side effects. Note: U parameter needed to help scalac's type inference.

Type parameters

U: the return type of f; the value is discarded, but the type parameter aids type inference

Value parameters

f: the function to apply to each element for its side effects

Attributes

Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Defines how to turn a given Iterable[A] into a collection of type C.

This process can be done in a strict way or a non-strict way (ie. without evaluating the elements of the resulting collections). In other words, this methods defines the evaluation model of the collection.

Value parameters

coll: the source collection to convert

Attributes

Returns: a new collection of type C containing the elements of coll
Note: When implementing a custom collection type and refining C to the new type, this method needs to be overridden (the compiler will issue an error otherwise). In the common case where C =:= CC[A], this can be done by mixing in the scala.collection.IterableFactoryDefaults trait, which implements the method using iterableFactory.

As witnessed by the @uncheckedVariance annotation, using this method might be unsound. However, as long as it is called with an Iterable[A] obtained from this collection (as it is the case in the implementations of operations where we use a View[A]), it is safe.
Inherited from:: IterableFactoryDefaults
Source: Iterable.scala

Partitions this view into a map of views according to some discriminator function.

        Note: Even when applied to a view or a lazy collection it will always force the elements.

Type parameters

K: the type of keys returned by the discriminator function.

Value parameters

f: the discriminator function.

Attributes

Returns

A map from keys to views such that the following invariant holds:

               (xs groupBy f)(k) = xs filter (x => f(x) == k)

         That is, every key `k` is bound to a view of those elements `x`
         for which `f(x)` equals `k`.

Inherited from:

IterableOps

Source

Iterable.scala

Partitions this view into a map of views according to a discriminator function key. Each element in a group is transformed into a value of type B using the value function.

It is equivalent to groupBy(key).mapValues(_.map(f)), but more efficient.

 case class User(name: String, age: Int)

 def namesByAge(users: Seq[User]): Map[Int, Seq[String]] =
   users.groupMap(_.age)(_.name)

        Note: Even when applied to a view or a lazy collection it will always force the elements.

Type parameters

B: the type of values returned by the transformation function
K: the type of keys returned by the discriminator function

Value parameters

f: the element transformation function
key: the discriminator function

Attributes

Returns: a map associating each key k produced by key with a view of values produced by applying f to elements that map to k
Inherited from:: IterableOps
Source: Iterable.scala

Partitions this view into a map according to a discriminator function key. All the values that have the same discriminator are then transformed by the f function and then reduced into a single value with the reduce function.

It is equivalent to groupBy(key).mapValues(_.map(f).reduce(reduce)), but more efficient.

 def occurrences[A](as: Seq[A]): Map[A, Int] =
   as.groupMapReduce(identity)(_ => 1)(_ + _)

        Note: Even when applied to a view or a lazy collection it will always force the elements.

Type parameters

B: the type of values returned by the transformation function
K: the type of keys returned by the discriminator function

Value parameters

f: the element transformation function
key: the discriminator function
reduce: the reduction function used to combine values mapped to the same key

Attributes

Returns: a map associating each key k produced by key with the reduction of all values produced by applying f to elements that map to k
Inherited from:: IterableOps
Source: Iterable.scala

Partitions elements in fixed size views.

Value parameters

size: the number of elements per group

Attributes

Returns: An iterator producing views of size size, except the last will be less than size size if the elements don't divide evenly.
See also: scala.collection.Iterator, method grouped
Inherited from:: IterableOps
Source: Iterable.scala

Selects the first element of this view.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Attributes

Returns: the first element of this view.
Throws: NoSuchElementException
if the view is empty.
Inherited from:: IterableOps
Source: Iterable.scala

Optionally selects the first element.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Attributes

Returns: the first element of this view if it is nonempty, None if it is empty.
Inherited from:: IterableOps
Source: Iterable.scala

The initial part of the collection without its last element.

        Note: Even when applied to a view or a lazy collection it will always force the elements.

Attributes

Inherited from:: IterableOps
Source: Iterable.scala

Iterates over the inits of this view. The first value will be this view and the final one will be an empty view, with the intervening values the results of successive applications of init.

        Note: Even when applied to a view or a lazy collection it will always force the elements.

Attributes

Returns: an iterator over all the inits of this view
Example: List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)
Inherited from:: IterableOps
Source: Iterable.scala

Tests whether this view can be repeatedly traversed. Always true for Iterables and false for Iterators unless overridden.

Attributes

Returns: true if it is repeatedly traversable, false otherwise.
Definition Classes: IterableOps -> IterableOnceOps
Inherited from:: IterableOps
Source: Iterable.scala

The companion object of this view, providing various factory methods.

Attributes

Returns: the companion factory object for this collection type
Note: When implementing a custom collection type and refining CC to the new type, this method needs to be overridden to return a factory for the new type (the compiler will issue an error otherwise).
Definition Classes: View -> Iterable -> IterableOps
Inherited from:: View
Source: View.scala

Selects the last element.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Attributes

Returns: The last element of this view.
Throws: NoSuchElementException
If the view is empty.
Inherited from:: IterableOps
Source: Iterable.scala

Optionally selects the last element.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Attributes

Returns: the last element of this view if it is nonempty, None if it is empty.
Inherited from:: IterableOps
Source: Iterable.scala

Analogous to zip except that the elements in each collection are not consumed until a strict operation is invoked on the returned LazyZip2 decorator.

Calls to lazyZip can be chained to support higher arities (up to 4) without incurring the expense of constructing and deconstructing intermediary tuples.

  val xs = List(1, 2, 3)
  val res = (xs lazyZip xs lazyZip xs lazyZip xs).map((a, b, c, d) => a + b + c + d)
  // res == List(4, 8, 12)

Type parameters

B: the type of the second element in each eventual pair

Value parameters

that: the iterable providing the second element of each eventual pair

Attributes

Returns: a decorator LazyZip2 that allows strict operations to be performed on the lazily evaluated pairs or chained calls to lazyZip. Implicit conversion to Iterable[(A, B)] is also supported.
Inherited from:: Iterable
Source: Iterable.scala

Builds a new view by applying a function to all elements of this view.

Type parameters

B: the element type of the returned view .

Value parameters

f: the function to apply to each element.

Attributes

Returns: a new view resulting from applying the given function f to each element of this view and collecting the results.
Inherited from:: IterableOps
Source: Iterable.scala

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The type over which the ordering is defined.

Value parameters

ord: An ordering to be used for comparing elements.

Attributes

Returns: the largest element of this view with respect to the ordering ord.
Throws: UnsupportedOperationException
if this view is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Finds the first element which yields the largest value measured by function f.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The result type of the function f.

Value parameters

f: The measuring function.
ord: An ordering to be used for comparing elements.

Attributes

Returns: the first element of this view with the largest value measured by function f with respect to the ordering ord.
Throws: UnsupportedOperationException
if this view is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Finds the first element which yields the largest value measured by function f.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The result type of the function f.

Value parameters

f: The measuring function.
ord: An ordering to be used for comparing elements.

Attributes

Returns: an option value containing the first element of this view with the largest value measured by function f with respect to the ordering ord.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The type over which the ordering is defined.

Value parameters

ord: An ordering to be used for comparing elements.

Attributes

Returns: an option value containing the largest element of this view with respect to the ordering ord.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The type over which the ordering is defined.

Value parameters

ord: An ordering to be used for comparing elements.

Attributes

Returns: the smallest element of this view with respect to the ordering ord.
Throws: UnsupportedOperationException
if this view is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Finds the first element which yields the smallest value measured by function f.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The result type of the function f.

Value parameters

f: The measuring function.
ord: An ordering to be used for comparing elements.

Attributes

Returns: the first element of this view with the smallest value measured by function f with respect to the ordering ord.
Throws: UnsupportedOperationException
if this view is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Finds the first element which yields the smallest value measured by function f.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The result type of the function f.

Value parameters

f: The measuring function.
ord: An ordering to be used for comparing elements.

Attributes

Returns: an option value containing the first element of this view with the smallest value measured by function f with respect to the ordering ord.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The type over which the ordering is defined.

Value parameters

ord: An ordering to be used for comparing elements.

Attributes

Returns: an option value containing the smallest element of this view with respect to the ordering ord.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Displays all elements of this view in a string.

Delegates to addString, which can be overridden.

Attributes

Returns: a string representation of this view. In the resulting string the string representations (w.r.t. the method toString) of all elements of this view follow each other without any separator string.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Displays all elements of this view in a string using a separator string.

Delegates to addString, which can be overridden.

Value parameters

sep: the separator string.

Attributes

Returns: a string representation of this view. In the resulting string the string representations (w.r.t. the method toString) of all elements of this view are separated by the string sep.
Example: List(1, 2, 3).mkString("|") = "1|2|3"
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Displays all elements of this view in a string using start, end, and separator strings.

Delegates to addString, which can be overridden.

Value parameters

end: the ending string.
sep: the separator string.
start: the starting string.

Attributes

Returns: a string representation of this view. The resulting string begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this view are separated by the string sep.
Example: List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Note that in the case of lazy collections (e.g. scala.collection.View or scala.collection.immutable.LazyList),

Attributes

Returns: a strict builder for the same collection type. it is possible to implement this method but the resulting Builder will break laziness. As a consequence, operations should preferably be implemented with fromSpecific instead of this method.
Note: When implementing a custom collection type and refining C to the new type, this method needs to be overridden (the compiler will issue an error otherwise). In the common case where C =:= CC[A], this can be done by mixing in the scala.collection.IterableFactoryDefaults trait, which implements the method using iterableFactory.

As witnessed by the @uncheckedVariance annotation, using this method might be unsound. However, as long as the returned builder is only fed with A values taken from this instance, it is safe.
Inherited from:: IterableFactoryDefaults
Source: Iterable.scala

Tests whether the view is not empty.

Attributes

Returns: true if the view contains at least one element, false otherwise.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

A pair of, first, all elements that satisfy predicate p and, second, all elements that do not.

The two view correspond to the result of filter and filterNot, respectively.

The default implementation provided here needs to traverse the collection twice. Strict collections have an overridden version of partition in StrictOptimizedIterableOps, which requires only a single traversal.

Value parameters

p: the predicate used to test elements

Attributes

Returns: a pair of views: the first containing all elements that satisfy p, the second containing those that do not
Inherited from:: IterableOps
Source: Iterable.scala

Applies a function f to each element of the view and returns a pair of views: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.

Example:

  val xs = $Coll(1, "one", 2, "two", 3, "three") partitionMap {
   case i: Int => Left(i)
   case s: String => Right(s)
  }
  // xs == ($Coll(1, 2, 3),
  //        $Coll(one, two, three))

Type parameters

A1: the element type of the first resulting collection
A2: the element type of the second resulting collection

Value parameters

f: the 'split function' mapping the elements of this view to an scala.util.Either

Attributes

Returns: a pair of views: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.
Inherited from:: IterableOps
Source: Iterable.scala

Multiplies together the elements of this collection.

The default implementation uses reduce for a known non-empty collection, foldLeft otherwise.

Note: will not terminate for infinite-sized collections.

Type parameters

B: the result type of the * operator.

Value parameters

num: an implicit parameter defining a set of numeric operations which includes the * operator to be used in forming the product.

Attributes

Returns: the product of all elements of this view with respect to the * operator in num.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Applies the given binary operator op to all elements of this view.

For each application of the operator, each operand is either an element of this view or another such application of the operator. The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation.

If this collection is ordered, then for any application of the operator, the element(s) appearing in the left operand will precede those in the right.

        Note: might return different results for different runs, unless either
        of the following conditions is met: (1) the operator is associative,
        and the underlying collection type is ordered; or (2) the operator is
        associative and commutative.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The type parameter for the binary operator, a supertype of A.

Value parameters

op: A binary operator; must be associative for the result to always be the same across runs.

Attributes

Returns: The result of applying op between all the elements if the view is nonempty.
Throws: UnsupportedOperationException
if this view is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Applies the given binary operator op to all elements of this view, going left to right.

"Going left to right" only makes sense if this collection is ordered: then if x,,1,,, x,,2,,, ..., x,,n,, are the elements of this view, the result is op( op( op( ... op(x,,1,,, x,,2,,) ... ), x,,n-1,,), x,,n,,).

If this collection is not ordered, then for each application of the operator, each right operand is an element. In addition, the leftmost operand is the first element of this view and each other left operand is itself an application of the operator. Each element appears exactly once in the computation.

        Note: might return different results for different runs, unless the
        underlying collection type is ordered or the operator is associative
        and commutative.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The result type of the binary operator, a supertype of A.

Value parameters

op: A binary operator.

Attributes

Returns: The result of applying op to all elements of this view, going left to right.
Throws: UnsupportedOperationException
if this view is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

If this view is nonempty, reduces it with the given binary operator op, going left to right.

The behavior is the same as reduceLeft except that the value is None if the view is empty. Each element appears exactly once in the computation.

        Note: might return different results for different runs, unless the
        underlying collection type is ordered or the operator is associative
        and commutative.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The result type of the binary operator, a supertype of A.

Value parameters

op: A binary operator.

Attributes

Returns: The result of reducing this view with op going left to right if the view is nonempty, inside a Some, and None otherwise.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

If this view is nonempty, reduces it with the given binary operator op.

The behavior is the same as reduce except that the value is None if the view is empty. The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation.

        Note: might return different results for different runs, unless either
        of the following conditions is met: (1) the operator is associative,
        and the underlying collection type is ordered; or (2) the operator is
        associative and commutative.

Note: will not terminate for infinite-sized collections.

Type parameters

B: A type parameter for the binary operator, a supertype of A.

Value parameters

op: A binary operator; must be associative for the result to always be the same across runs.

Attributes

Returns: The result of reducing this view with op if the view is nonempty, inside a Some, and None otherwise.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Applies the given binary operator op to all elements of this view, going right to left.

"Going right to left" only makes sense if this collection is ordered: then if x,,1,,, x,,2,,, ..., x,,n,, are the elements of this view, the result is op(x,,1,,, op(x,,2,,, op( ... op(x,,n-1,,, x,,n,,) ... ))).

If this collection is not ordered, then for each application of the operator, each left operand is an element. In addition, the rightmost operand is the last element of this view and each other right operand is itself an application of the operator. Each element appears exactly once in the computation.

        Note: might return different results for different runs, unless the
        underlying collection type is ordered or the operator is associative
        and commutative.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The result type of the binary operator, a supertype of A.

Value parameters

op: A binary operator.

Attributes

Returns: The result of applying op to all elements of this view, going right to left.
Throws: UnsupportedOperationException
if this view is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

If this view is nonempty, reduces it with the given binary operator op, going right to left.

The behavior is the same as reduceRight except that the value is None if the view is empty. Each element appears exactly once in the computation.

        Note: might return different results for different runs, unless the
        underlying collection type is ordered or the operator is associative
        and commutative.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The result type of the binary operator, a supertype of A.

Value parameters

op: A binary operator.

Attributes

Returns: The result of reducing this view with op going right to left if the view is nonempty, inside a Some, and None otherwise.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Attributes

Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Computes a prefix scan of the elements of the collection.

Note: The neutral element z may be applied more than once.

Type parameters

B: element type of the resulting collection

Value parameters

op: the associative operator for the scan
z: neutral element for the operator op

Attributes

Returns: a new view containing the prefix scan of the elements in this view
Inherited from:: IterableOps
Source: Iterable.scala

Produces a view containing cumulative results of applying the operator going left to right, including the initial value.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Type parameters

B: the type of the elements in the resulting collection

Value parameters

op: the binary operator applied to the intermediate result and the element
z: the initial value

Attributes

Returns: collection with intermediate results
Inherited from:: IterableOps
Source: Iterable.scala

Produces a collection containing cumulative results of applying the operator going right to left. The head of the collection is the last cumulative result.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered.

        Note: Even when applied to a view or a lazy collection it will always force the elements.

Example:

  List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)

Type parameters

B: the type of the elements in the resulting collection

Value parameters

op: the binary operator applied to the intermediate result and the element
z: the initial value

Attributes

Returns: collection with intermediate results
Inherited from:: IterableOps
Source: Iterable.scala

The size of this view.

Note: will not terminate for infinite-sized collections.

Attributes

Returns: the number of elements in this view.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Compares the size of this view to the size of another Iterable.

Value parameters

that: the Iterable whose size is compared with this view's size.

Attributes

Returns

A value x where

     x <  0       if this.size <  that.size
     x == 0       if this.size == that.size
     x >  0       if this.size >  that.size

The method as implemented here does not call size directly; its running time is O(this.size min that.size) instead of O(this.size + that.size). The method should be overridden if computing size is cheap and knownSize returns -1.

Inherited from:

IterableOps

Source

Iterable.scala

Compares the size of this view to a test value.

Value parameters

otherSize: the test value that gets compared with the size.

Attributes

Returns

A value x where

     x <  0       if this.size <  otherSize
     x == 0       if this.size == otherSize
     x >  0       if this.size >  otherSize

The default implementation does not call size, which may be arbitrarily expensive. It will use knownSize if nonnegative. Otherwise, it will iterate to compute an element count, with complexity O(size min otherSize). This method should be overridden if computing size is cheap and knownSize returns -1. In that case, the custom implementation should just compare size and otherSize directly.

See also

sizeIs

Inherited from:

IterableOps

Source

Iterable.scala

Returns a value class containing operations for comparing the size of this view to a test value.

These operations are implemented in terms of `sizeCompare(Int)`, and allow the following more readable usages:

this.sizeIs < size     // this.sizeCompare(size) < 0
this.sizeIs <= size    // this.sizeCompare(size) <= 0
this.sizeIs == size    // this.sizeCompare(size) == 0
this.sizeIs != size    // this.sizeCompare(size) != 0
this.sizeIs >= size    // this.sizeCompare(size) >= 0
this.sizeIs > size     // this.sizeCompare(size) > 0

Attributes

Returns: a wrapper that allows size comparisons using operators such as =, and >
Inherited from:: IterableOps
Source: Iterable.scala

Selects an interval of elements. The returned view is made up of all elements x which satisfy the invariant:

  from <= indexOf(x) < until

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters

from: the lowest index to include from this view.
until: the lowest index to EXCLUDE from this view.

Attributes

Returns: a view containing the elements greater than or equal to index from extending up to (but not including) index until of this view.
Example: List('a', 'b', 'c', 'd', 'e').slice(1, 3) == List('b', 'c')
Inherited from:: IterableOps
Source: Iterable.scala

Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped).

The returned iterator will be empty when called on an empty collection. The last element the iterator produces may be smaller than the window size when the original collection isn't exhausted by the window before it and its last element isn't skipped by the step before it.

Value parameters

size: the number of elements per group
step: the distance between the first elements of successive groups

Attributes

Returns: An iterator producing views of size size, except the last element (which may be the only element) will be smaller if there are fewer than size elements remaining to be grouped.
See also: scala.collection.Iterator, method sliding
Example: List(1, 2, 3, 4, 5).sliding(2, 2) = Iterator(List(1, 2), List(3, 4), List(5))

List(1, 2, 3, 4, 5, 6).sliding(2, 3) = Iterator(List(1, 2), List(4, 5))
Inherited from:: IterableOps
Source: Iterable.scala

Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped).

An empty collection returns an empty iterator, and a non-empty collection containing fewer elements than the window size returns an iterator that will produce the original collection as its only element.

Value parameters

size: the number of elements per group

Attributes

Returns: An iterator producing views of size size, except for a non-empty collection with less than size elements, which returns an iterator that produces the source collection itself as its only element.
See also: scala.collection.Iterator, method sliding
Example: List().sliding(2) = empty iterator

List(1).sliding(2) = Iterator(List(1))

List(1, 2).sliding(2) = Iterator(List(1, 2))

List(1, 2, 3).sliding(2) = Iterator(List(1, 2), List(2, 3))
Inherited from:: IterableOps
Source: Iterable.scala

Splits this view into a prefix/suffix pair according to a predicate.

Note: c span p is equivalent to (but possibly more efficient than) (c takeWhile p, c dropWhile p), provided the evaluation of the predicate p does not cause any side effects.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters

p: the test predicate

Attributes

Returns: a pair consisting of the longest prefix of this view whose elements all satisfy p, and the rest of this view.
Inherited from:: IterableOps
Source: Iterable.scala

Splits this view into a prefix/suffix pair at a given position.

Note: c splitAt n is equivalent to (but possibly more efficient than) (c take n, c drop n).

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters

n: the position at which to split.

Attributes

Returns: a pair of views consisting of the first n elements of this view, and the other elements.
Definition Classes: IterableOps -> IterableOnceOps
Inherited from:: IterableOps
Source: Iterable.scala

Returns a scala.collection.Stepper for the elements of this collection.

The Stepper enables creating a Java stream to operate on the collection, see scala.jdk.StreamConverters. For collections holding primitive values, the Stepper can be used as an iterator which doesn't box the elements.

The implicit scala.collection.StepperShape parameter defines the resulting Stepper type according to the element type of this collection.

For collections of Int, Short, Byte or Char, an scala.collection.IntStepper is returned
For collections of Double or Float, a scala.collection.DoubleStepper is returned
For collections of Long a scala.collection.LongStepper is returned
For any other element type, an scala.collection.AnyStepper is returned

Note that this method is overridden in subclasses and the return type is refined to S with EfficientSplit, for example scala.collection.IndexedSeqOps.stepper. For Steppers marked with scala.collection.Stepper.EfficientSplit, the converters in scala.jdk.StreamConverters allow creating parallel streams, whereas bare Steppers can be converted only to sequential streams.

Type parameters

S: the type of the returned Stepper, determined by the implicit StepperShape

Value parameters

shape: the StepperShape that determines the concrete Stepper subtype to return

Attributes

Returns: a Stepper over the elements of this view, using a primitive-typed Stepper subclass for Int/Long/Double (and related) element types
Inherited from:: IterableOnce
Source: IterableOnce.scala

Sums the elements of this collection.

The default implementation uses reduce for a known non-empty collection, foldLeft otherwise.

Note: will not terminate for infinite-sized collections.

Type parameters

B: the result type of the + operator.

Value parameters

num: an implicit parameter defining a set of numeric operations which includes the + operator to be used in forming the sum.

Attributes

Returns: the sum of all elements of this view with respect to the + operator in num.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

The rest of the collection without its first element.

Attributes

Inherited from:: IterableOps
Source: Iterable.scala

Iterates over the tails of this view. The first value will be this view and the final one will be an empty view, with the intervening values the results of successive applications of tail.

Attributes

Returns: an iterator over all the tails of this view
Example: List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)
Inherited from:: IterableOps
Source: Iterable.scala

Selects the first n elements.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters

n: the number of elements to take from this view.

Attributes

Returns: a view consisting only of the first n elements of this view, or else the whole view, if it has less than n elements. If n is negative, returns an empty view.
Inherited from:: IterableOps
Source: Iterable.scala

Selects the last n elements.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters

n: the number of elements to take from this view.

Attributes

Returns: a view consisting only of the last n elements of this view, or else the whole view, if it has less than n elements. If n is negative, returns an empty view.
Inherited from:: IterableOps
Source: Iterable.scala

Takes longest prefix of elements that satisfy a predicate.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters

p: The predicate used to test elements.

Attributes

Returns: the longest prefix of this view whose elements all satisfy the predicate p.
Inherited from:: IterableOps
Source: Iterable.scala

Applies a side-effecting function to each element in this collection. Strict collections will apply f to their elements immediately, while lazy collections like Views and LazyLists will only apply f on each element if and when that element is evaluated, and each time that element is evaluated.

Type parameters

U: the return type of f

Value parameters

f: a function to apply to each element in this view

Attributes

Returns: The same logical collection as this
Definition Classes: IterableOps -> IterableOnceOps
Inherited from:: IterableOps
Source: Iterable.scala

Given a collection factory factory, converts this view to the appropriate representation for the current element type A. Example uses:

import scala.collection.mutable.ArrayBuffer
import scala.collection.immutable.BitSet
val xs: Iterable[Int] = Seq(1, 2, 3, 4, 5)
    xs.to(List)
    xs.to(ArrayBuffer)
    xs.to(BitSet) // for xs: Iterable[Int]

Type parameters

C1: the target collection type

Value parameters

factory: the factory for the target collection type

Attributes

Returns: a new collection of type C1 containing all elements of this view
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Converts this view to an Array.

Implementation note: DO NOT call Array.from from this method.

Type parameters

B: The type of elements of the result, a supertype of A.

Attributes

Returns: This view as an Array[B].
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Converts this view to a Buffer.

Type parameters

B: The type of elements of the result, a supertype of A.

Attributes

Returns: This view as a Buffer[B].
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Converts this view to an IndexedSeq.

Attributes

Returns: This view as an IndexedSeq[A].
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Converts this view to a List.

Attributes

Returns: This view as a List[A].
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Converts this view to a Map, given an implicit coercion from the view's type to a key-value tuple.

Type parameters

K: The key type for the resulting map.
V: The value type for the resulting map.

Value parameters

ev: an implicit evidence that A is a subtype of (K, V)

Attributes

Returns: This view as a Map[K, V].
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Attributes

Returns: This view as a Seq[A]. This is equivalent to to(Seq) but might be faster.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Converts this view to a Set.

Type parameters

B: The type of elements of the result, a supertype of A.

Attributes

Returns: This view as a Set[B].
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Converts this view to a string.

Attributes

Returns: a string representation of this collection. By default this string consists of the className of this view, followed by all elements separated by commas and enclosed in parentheses.
Definition Classes: View -> Iterable -> Any
Inherited from:: View
Source: View.scala

Converts this view to a Vector.

Attributes

Returns: This view as a Vector[A].
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Transposes this view of iterable collections into a view of views.

The resulting collection's type will be guided by the static type of view. For example:

val xs = List(
           Set(1, 2, 3),
           Set(4, 5, 6)).transpose
// xs == List(
//         List(1, 4),
//         List(2, 5),
//         List(3, 6))

val ys = Vector(
           List(1, 2, 3),
           List(4, 5, 6)).transpose
// ys == Vector(
//         Vector(1, 4),
//         Vector(2, 5),
//         Vector(3, 6))

        Note: Even when applied to a view or a lazy collection it will always force the elements.

Type parameters

B: the type of the elements of each iterable collection.

Value parameters

asIterable: an implicit conversion which asserts that the element type of this view is an Iterable.

Attributes

Returns: a two-dimensional view of views which has as nth row the nth column of this view.
Throws: IllegalArgumentException
if all collections in this view are not of the same size.
Inherited from:: IterableOps
Source: Iterable.scala

Converts this view of pairs into two collections of the first and second half of each pair.

  val xs = $Coll(
             (1, "one"),
             (2, "two"),
             (3, "three")).unzip
  // xs == ($Coll(1, 2, 3),
  //        $Coll(one, two, three))

Type parameters

A1: the type of the first half of the element pairs
A2: the type of the second half of the element pairs

Value parameters

asPair: an implicit conversion which asserts that the element type of this view is a pair.

Attributes

Returns: a pair of views, containing the first, respectively second half of each element pair of this view.
Inherited from:: IterableOps
Source: Iterable.scala

Converts this view of triples into three collections of the first, second, and third element of each triple.

  val xs = $Coll(
             (1, "one", '1'),
             (2, "two", '2'),
             (3, "three", '3')).unzip3
  // xs == ($Coll(1, 2, 3),
  //        $Coll(one, two, three),
  //        $Coll(1, 2, 3))

Type parameters

A1: the type of the first member of the element triples
A2: the type of the second member of the element triples
A3: the type of the third member of the element triples

Value parameters

asTriple: an implicit conversion which asserts that the element type of this view is a triple.

Attributes

Returns: a triple of views, containing the first, second, respectively third member of each element triple of this view.
Inherited from:: IterableOps
Source: Iterable.scala

A view over the elements of this collection.

Attributes

Definition Classes: View -> IterableOps
Inherited from:: View
Source: View.scala

Creates a non-strict filter of this view.

Note: the difference between c filter p and c withFilter p is that the former creates a new collection, whereas the latter only restricts the domain of subsequent map, flatMap, foreach, and withFilter operations.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters

p: the predicate used to test elements.

Attributes

Returns: an object of class WithFilter, which supports map, flatMap, foreach, and withFilter operations. All these operations apply to those elements of this view which satisfy the predicate p.
Inherited from:: IterableOps
Source: Iterable.scala

Returns a view formed from this view and another iterable collection by combining corresponding elements in pairs. If one of the two collections is longer than the other, its remaining elements are ignored.

Type parameters

B: the type of the second half of the returned pairs

Value parameters

that: The iterable providing the second half of each result pair

Attributes

Returns: a new view containing pairs consisting of corresponding elements of this view and that. The length of the returned collection is the minimum of the lengths of this view and that.
Inherited from:: IterableOps
Source: Iterable.scala

Returns a view formed from this view and another iterable collection by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.

Type parameters

A1: the type of the first element in each result pair (supertype of A)
B: the type of the second element in each result pair

Value parameters

that: the iterable providing the second half of each result pair
thatElem: the element to be used to fill up the result if that is shorter than this view.
thisElem: the element to be used to fill up the result if this view is shorter than that.

Attributes

Returns: a new view containing pairs consisting of corresponding elements of this view and that. The length of the returned collection is the maximum of the lengths of this view and that. If this view is shorter than that, thisElem values are used to pad the result. If that is shorter than this view, thatElem values are used to pad the result.
Inherited from:: IterableOps
Source: Iterable.scala

Zips this view with its indices.

Attributes

Returns: A new view containing pairs consisting of all elements of this view paired with their index. Indices start at 0.
Example: List("a", "b", "c").zipWithIndex == List(("a", 0), ("b", 1), ("c", 2))
Inherited from:: IterableOps
Source: Iterable.scala

ScanLeft

Attributes

Members list

Value members

Concrete methods

Attributes

Attributes

Attributes

Inherited methods

Type parameters

Value parameters

Attributes

Value parameters

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